[alt-photo] Re: Gum over cyanotype question

[Willen, Matthew S]

Thanks Chris, it's been enjoyable watching all the responses, and I was
wondering to myself yesterday if my question had in fact been answered.

I appreciate the suggestions. I've noticed the prolonged exposure with the
burnt sienna and yellow. Not so much with black though.

Just wondering why you capitalized NO in the NO tween in the gum layer?
Was that for emphasis? Is there an incompatibility between tween and the
cyanotype?

One post had mentioned alkalinity of the water perhaps being suspect. I
have well water, and all of the bedrock around here is limestone, and we
have had tons of rain in the past few months, and so I think that may be
worth looking into, for a host of reasons.

Anyway, I have a couple more days of teaching to progressively smaller
classes before our spring break begins. Then I'll have some time to tease
some things out. 

Thanks. Matt

On 2/28/12 1:41 PM, "Christina Anderson" <zphoto at montana.net> wrote:

>Matt,
>I haven't read all the answers yet, so forgive me if this has been
>answered; trying to clean out my inbox.
>
>Burnt sienna for me takes a LONG exposure. 15 minutes is even not too
>long. I don't know why this is the case--whether an earth pigment is more
>opaque to light or not, but I find that yellow, burnt sienna, and black
>expose from longer to longest in that order, and though I choose a
>standard printing time around 6 minutes, thalo is happy with 4 or 5,
>magenta 5 or 6, yellow 9, burnt sienna a sort of whoops I left it in the
>UVBL longer so what, and black 9-15 as well. I know this sounds really
>loose and unscientific, but I am just not so rigorous when my timer goes
>off to get back into the dimroom and remove the contact frame from the
>UVBL unit. But I will say that actually I have tested all colors with a
>step wedge and found this to be true as well.
>
>It is hard to be exact about this because I find that gum can expose at
>all kinds of minutes/choices. I use a 6 minute ballpark because it
>provides a layer that is very stable in development and will allow some
>spray development in the beginning five or ten minutes.
>
>I use 15% ammonium dichromate 1:1 with gum/pigment.
>
>I have never had the cyanotype layer determine whether or not the gum
>sloughs off or not.
>
>Any part of the cyanotype that is covered by a gum layer does not wash
>out for me.
>
>NO tween in the gum layer.
>
>Slickness and sloughing off in my experience is more determined by too
>thick a layer of gum, not enough exposure, too much sizing.
>
>Hope at least one of these points helps.
>
>Chris
>
>Christina Z. Anderson
>christinaZanderson.com
>
>On Feb 27, 2012, at 8:52 AM, Willen, Matthew S wrote:
>
>> Hi All,
>> I am working on some duotone prints using a cyanotype layer on the
>>bottom and gum layer of an umber or sienna over the top. I'm using a
>>stock solution of cyanotype from B/S. A couple of things happen: 1) I
>>find that the gum layer doesn't stick particularly well to the
>>cyanotype, it almost peels off; and 2) even though I wash throughly and
>>all the cyanotype layer to dry well, I lose a lot of the density of that
>>layer in the extended gum wash. Any suggestions? Perhaps some tween in
>>the gum layer? I've also developed the cyanotype in a Hydrogen
>>peroxide/H20 solution. Might that make it more slick? Thanks.
>> 
>> Matt
>> _______________________________________________
>> Alt-photo-process-list | http://altphotolist.org/listinfo
>
>_______________________________________________
>Alt-photo-process-list | http://altphotolist.org/listinfo